Hydrogenation catalyst and method of preparing the same



Patented July 16, 1940 UNITED STATES PATENT OFFICE HYDROGENATIONCATALYST AND METHOD OF PREPARING THE SAME No Drawing. ApplicationJanuary 25, 1938,

Serial No. 186,906

20 Claims. 23-236) This invention relates to improvements in catalytichydrogenation, and more particularly to new forms of noble metalcatalysts and their production, and to hydrogenation by the use of 6such catalysts.

The catalyst in accordance with this invention comprises an inert,porous support, impregnated with an adherent deposit of a noble metaloxide, which is immediately upon contact with hydrogen, reduced to avery active form of noble metal. The inert, porous support may consistof fine, porous materials, for example, diatomaceous earth, pumice,etc., or of porous granules of silica or alumina. It may also consist ofa continuous,

porous support, formed, for example, of a mass of silica granules bondedtogether. Such support, and the catalyst thereby produced, is describedand claimed in my copending application, Ser. No. 753,132, filedNovember 15, 1934.

20 The inert, porous support is impregnated, in accordance with thisinvention, with a mixture of chloroplatinic or chloropalladous acid andan alkali metal nitrate, for example, sodium nitrate, potassium nitrate,lithium nitrate, etc., and is 25 then heated to a temperature of about300- 500 C., to efiect reaction between the acid and the nitrate, withresulting formation of platinum oxide or palladium oxide. The materialso produced is ready for' use as a hydrogenation cata- 30 lyst, sincethe oxide is immediately reduced to the metal upon contact withhydrogen. 1 Impregnation of the porous base or support I have found tobe accomplished by reacting a concentrated, aqueous solution of thenitrate 85 with a concentrated, aqueous solution of eitherchloroplatinic or chloropalladous acid. The nitrate should be employedin an amount which varies between the stoichiometric equivalent andabout a 50% excess thereof. Six mols of sodium 40 nitrate react with 1mol of chloroplatinic acid. According to my process, the nitrate shouldbe utilized in an amount between 6 and 9 mols for.

each mol of the chloroplatinic acid. Similarly, 4 mols of sodium nitratereact .with 1 mol of 45 chloropalladous acid, and according to myprocess the nitrate should be used preferably in amounts between fourand six mols for each mol of chloropalladous acid.

The two compounds are, preferably, dissolved 50 in the minimum amount ofwater possible. De-

sirably, complete solution is effected by heating the solution, and thehot solution is used to impregnate the porous support, which, desirably,has been heated to about the temperature of the solution. Theimpregnated carrier is then slowly heated, preferably in an electricoven, desirably to about 375-400 0., although a temperature within therange oi'about 300 to about 500 C. maybe used, and is held at thistemperature for about one hour. A temperature higher 5 than about 500 C.is undesirable, because of combination between the noble metal oxideformed and the silica of the bias or support, and also causes theformation of an inert catalyst and prevents the formation of an adherentdeposit of 10 the noble metal oxide. The impregnated carrier is thencooled, washed with water until free of 'soluble impurities, and dried.The porous support is now found to be impregnated with platinum oxide orpalladium oxide, which is, however, 16 in the presence of hydrogen,immediately reduced to a very active form of platinum or palladium.

As illustrative of the procedure for forming a catalyst in accordancewith this invention, the 20 following examples are given:

Example I Filtros, which comprises a mass of silica granules bondedtogether with a synthetic silicate, broken into pieces 3 to 5 mesh, wasthoroughly cleansed and dried. To 25 grams of this material was added ahot solution containing 6.8 grams of sodium nitrate and 1.6 grams ofplatinum in the form of, chloroplatinic acid. This mixture was thenplaced in an oven and heated slowly to 400 C. and maintained at suchtemperature for about minutes. The mixture was then cooled, washed anddried.

Example II Ten grams of diatomaceous earth were mixed with a solutionconsisting of 5 cc. of chloroplatinicacid (0.4 g. of platinum per 00.),5 grams of water and 5 grams of sodium nitrate. This 40 solution barelymoistened the diatomaceous earth after thorough mixing. The mixture washeated in an oven as in Example I,'cooled. washed, and dried.

Eaample III Hydrogenation may be accomplished with the use oi the noblemetal catalyst, in accordance with this invention; by placing thecatalyst in a suitable supporting vessel or container and circulatingthe material to be hydrogenated, in liquid or vapor phase, past thecatalyst, in the presence of hydrogen. Desirably, the current ofhydrogen will also be caused to flow past the catalyst, and, in suchcases, the flow of hydrogen may be either concurrent with, or, where thematerial' is in liquid phase, counter-current to the flow of materialto. be hydrogenated. Uniform distribution of the material, if in liquidphase, over the catalyst, may be efiected by spraying it, atomized by acurrent of hydrogen, from a suitable nozzle. Where the material to behydrogenated is a solid, or a liquid of high viscosity. it may bedissolved in an inert solvent, for example, methyl, ethyl, propyl,isopropyl, or butyl alcohols, glacial acetic acid, gasoline, mixedsolvents, etc., and hydrogenated in such solution. The hydrogenationwill, desirably, be conducted at a temperature of from about 10 C. toabout 00 0., although the use of any particular temperature is, in noway, essential to the procedure. The particular pressure employed is,likewise, non-essential, but a pressure of from atmospheric to about1000 atmospheres may be used. The rate of hydrogenation may becontrolled by regulating the hydrogen pressure.

- Any material capable of hydrogenation, for example, vegetable oils,unsaturated fatty acids, olefins, aromatic hydrocarbons, derivatives ofthe latter, etc., may be hydrogenated in accordance, with this inventionby the use of the noble metal catalyst described above. Materialscontaining the abietyl radical, for example, rosin, abietic acid, estersthereof, such as methyl abietate, ethylabietate, glyceryl abietate, gycol abietate, etc., abietyl alcohol, rosin oil, terpenes, such as pineoil, alpha-terpineol, alpha-terpinene, dipentene, pinene, polymerizedterpenes, etc., may readily be hydrogenated by the above-describedprocedure, using the noble metal catalyst in accordance with thisinvention.

As illustrative of such hydrogenation procedure, the following examplesare given:

Example IV The catalyst described in Example I was placed in a glasscontainer having a porous, false bottom of fritted glass, and a bottominlet. The catalyst was covered with a solution containing of methylabietate in glacial acetic acid. Hydrogen was passed upward through theporous bottom for 6 hours at room temperature, a well-distributed sprayof fine hydrogen bubbles being formed. The product, on separation fromthe acetic acid, showed 57% hydrogenation.

Example V The catalyst described in Example II,was shaken in aBurgess-Parr apparatus with various solutions, at room temperature andat -40 pounds hydrogen pressure. Typical results secured were asfollows:

(a) With 25% ethyl abietate in glacial acetic acid, 79% saturation wasobtained in 150 minutes.

(b) With 25% methyl abietate in glacial acetic acid, 64% saturation wasobtained in 150 minutes.

(0) With 25% I wood rosin in ethyl alcohol solution, 72% saturation wasobtained in 240 minutes.

Example VI The catalyst described in Example III was shaken with rosinin alcohol solution, 2% of palladium, based on the rosin, being used, atroom temperature and at 25-40 pounds pressure of hydrogen. Alter 120minutes, 75% saturation of the rosin was obtained.

Example VII Three Filtros discs, each 3 inches in diameter and 1 inchesthick were cleaned, dried, and each impregnated with 70 cc. of solutioncontaining grams of sodium nitrate and 7.5 grams of platinum, aschloroplatinic acid. These impregnated discs were heated slowly to 4000., held at this temperature for 90 minutes, cooled, washed free ofsoluble impurities, and dried. The discs were then cemented togetheralong their peripheries only, and a solution containing 25% I woodrosin, in solution in ethyl alcohol, was circulated through the discs atthe rate of 1000 cc. per hour, in the presence of a concurrent flow ofhydrogen at room temperature. The rosin, on recovery from the solution,showed a saturation of of both double bonds.

Applicants catalyst is a marked improvement over the prior art. It isknown. for example, from J. Am. Chem. Soc. 45, 2171-9 (1923) to preparea platinum catalyst by the use of large excesses oi sodium nitrate (705%excess), but no method of supporting said catalyst. The preparation ofsuch catalyst in a molten state suggested no way of supporting the samewhen produced. Introduction of refractory supports in the fusion led tono useful result.

Said prior art catalyst is produced by the use of temperatures between5004550 C. On the contrary, the catalyst in accordance with the presentinvention is produced at a temperature of 300-500 0., preferably 400 C.,and I have found that heating to above 500 C. causes inactivity of thecatalyst. ).A real problem was present in the art prior to thisinvention. The only feasible methods available in the prior art for thehydrogenation ofrosin consisted in the use of very high hydrogenpressures, i. e., about 4000 lbs. per sq. in., high temperatures, 1. e.,180-220 C., and a base metal catalyst, particularly nickel. Theseconditions involved a high cost of plant and very hazardous workingconditions, due to the high pressures and dangerous character ofhydrogen explosions.

If a noble metal catalyst could be used, room temperature and verymoderate pressures, e. g., 30-40 lbs. per sq. in., could be used, thusgreatly reducing plant cost and danger of injury to life and limb.However, before this invention there was no known noble metal catalystsuitable for this purpose, due to the utter impossibility oi! reducingcatalyst losses to a feasible point, when using a finely divided orcolloidal catalyst. Catalysts useful in oxidation reactions, such asplatinum gauze or platinized asbestos, showed no activity whatever forhydrogenation purposes. Catalysts on inert supports, but reduced withformaldehyde or iormates showed only a moderate hydrogenation activity.The prior art Adams catalyst had good hydrogenation activity, but nomethod of supporting the same was known. The preparation 01' the Adamscatalyst, as disclosed, in molten alkali nitrate fusion, suggested noway of supporting the same. Attempts to introduce refractory supports,e. g., asbestos, into the fused 450 C. to form platinum oxide, andextracting mass, were without result, for the reason that the noblemetal oxide had no preferential afilnity to form on the surface of thesupport and little or no firm adhesion to the support after formation.

Contrary to the above, my improved method produces a superiorhydrogenation, noble metal catalyst of high activity, e. g., in thediflicult hydrogenation of rosin, and a catalyst in which the noblemetal adheres firmly and uniformly to the porous support material.Furthermore, the conditions of my process are critical to produce theimproved noble metal catalyst. Temperatures in excess of thetemperatures I use produce inactive catalysts. The large excesses ofalkali nitrate used in the prior art render preparation of a catalystuneconomical, since the use of a large excess of alkali nitrate couldonly be obtained by reducing the proportion of soluble noble metalcompound present, due to the definitely limited solubility. Thus, theuse of impregnation from solution is necessary and critical to obtaineven distribution over the support material and thus obtain themicroscopic film thickness necessary for flrm adhesion to the supportmaterial.

I have found that when grams of rosin and 150 cc. ethyl alcohol wereshaken with the reduced platinum of the prior art catalyst under apressure of 24 atmospheres of hydrogen, a 48% saturation of the doublebonds of the rosin resulted in minutes, and continuation of thetreatmentfor 3 hours produced only 49% saturation. On the other hand,with the process and catalyst in accordance with this invention, inwhich only 0.85 grams of platinum had been deposited upon an inert,porous base, and with like conditions of hydrogenation, there resulted63.2% saturation in 25 minutes, 67.3% in minutes, and 69.5% in minutes.The catalyst produced in'accordance with this invention avoids thedifilculties experienced by the use of prior art catalysts. It possessesa superior activity in the hydrogenation of rosin, large quantities ofhighly active catalyst, in form readily adapted for commercialhydrogenation may be prepared easily and conveniently, the improvedcatalyst adheres firmly and uniformly to the catalyst support and isreadily filtrable to reduce handling and operating losses.

It will be understood that the examples and details of procedurehereinabove set forth are illustrative only and are not in limitation ofthe invention herein disclosed.

' I have not specifically claimed, in this application, my hereindescribed invention insofar as it relates to a procedure for thehydrogenation of unsaturated compounds and, in particular, Y

porous support material with a concentrated aqueous solution ofchloroplatinic acid and a concentrated aqueous solution of an alkalimetal nitrate, heating the impregnated material at a temperature of fromabout 300 C. to about water-soluble impurities from the impregnatedmaterial, the ratio between the chloroplatinic acid and the alkali metalnitrate present being such that a deposit of platinum oxide firmlyadherent to the support is formed. 2. The method of preparing ahydrogenatio catalyst which includes impregnating an inert, poroussupport material with a concentrated aqueous solution of chloropalladousacid and a concentrated aqueous solution of an alkali metal nitrate,heating the impregnated material at a temperature of from about 300 C.to about 450 C. to form palladium oxide, and extracting water-solubleimpurities from the impregnated material, the ratio between thechloropalladous acid and the alkali metal nitrate present being suchthat a deposit of palladium oxide firmly adherent to the support isformed.

3. The method of preparing a hydrogenation catalyst which includesimpregnating an inert,

porous support material with a concentrated aqueous solution of a noblemetal compound, from the group consisting of-platinum compounds andpalladium compounds, and a concentrated aqueous solution of an alkalimetal nitrate, heating the impregnated material at a temperature of fromabout 300 C. to about 450 C. to form a noble metal oxide, and extracting water-soluble impurities from the impregnated material, theratio between noble metal compound and the alkali metal nitrate presentbeing such that a deposit of noble metal oxide firmly adherent to thesupport is formed.

4. The method of preparing a hydrogenation catalyst which includesimpregnating an inert, porous support material with a concentratedaqueous solution of a soluble platinum compound and a concentratedaqueous solution of an alkali metal nitrate, heating the impregnatedmaterial at a. temperature of from about 300 C. to about 450 C. to formplatinum oxide, and extracting water-soluble impurities from theimpregnated material, the ratio between the platinum compound and thealkali metal nitrate present being such that a deposit of platinum oxidefirmly adherent to the support is formed.

5. The method of preparing a hydrogenation catalyst which includesimpregnating an inert, porous support material with a concentratedaqueous solution of a soluble palladium compound and a concentratedaqueous solution of an alkali metal nitrate, heating the impregnatedmaterial at a temperature of from about 300 C. to'about 450 C. to formpalladium oxide, and extracting water-soluble impurities from theimpregnated material, the ratio between the palladium compound and thealkali metalnitrate present being such that a deposit of palladium oxidefirmly adherent to the support is formed.

6. A hydrogenation catalyst comprising an inporous support materialuniformly imoxide formed within the porous support material by thereaction of a concentrated aqueous solution of an alkali metal nitrateupon a concentrated aqueous solution of a water soluble platinumcompound at an elevated temperature not exceeding approximately 450 C.

8. A hydrogenation catalyst comprising an inert, porous support materialuniformly impregnated with an adherent deposit of palladium oxide formedwithin the porous support material by the reaction of a concentratedaqueous solution of an alkali metal nitrate upon a concentrated aqueoussolution of a water soluble palladium compound at an elevatedtemperature not exceeding approximately 450 C;

9. The method of preparing a hydrogenation catalyst which includesimpregnating an inert, porous support material with a concentratedaqueous solution of a water-soluble tetravalent platinum compound and aconcentrated aqueous solution of an alkali metal nitrate in theproportion of about nine molar weights of nitrate to one atomic weightof tetravalent platinum present in the platinum compound, heating theimpregnated material at a temperature of from about 300 C. to about 450C. to form platinum oxide, and extracting water-soluble impurities fromthe impregnated material.

10. The method of preparing a hydrogenation catalyst which includesimpregnating an inert, porous support material with a mixture of aconcentrated aqueous solution of chloroplatinic acid and a concentratedaqueous solution of an alkali metal nitrate in the proportion of aboutnine molar weights of nitrate to one molar weight of chloroplatinicacid, heating the impregnated material at a temperature of from about300 C. to about 450 C. to form platinum oxide, and extractingwater-soluble impurities from the impregnated material.

11. The method of preparing a hydrogenation catalyst which includesimpregnating an inert, porous support material with a concentratedaqueous solution of a water-soluble divalent palladium compound and aconcentrated aqueous solution of an alkali metal nitrate in theproportion of about four molar weights of nitrate to one atomic weightof divalent palladium present in the palladium compound, heating theimpregnated material at a temperature of from about 300 C. to about 450C. to form palladium oxide, and extracting water-soluble impurities fromthe impregnated material.

12. The method of preparing a hydrogenation catalyst which includesimpregnating an inert, porous support material with a mixture ofa'concentrated aqueous solution of chloropalladous acid and aconcentrated aqueous solution of an alkali metal nitrate in theproportion of about four molar weights of nitrate to one molar weight ofchloropalladous acid, heating the impregnated material at a temperatureof from about 300 C. to about 450 C. to form palladium oxide, andextracting water-soluble impurities from the impregnated material.

13. The method of preparing a hydrogenation catalyst which includesimpregnating an inert, porous support material with a concentratedaqueous solution of a water-soluble tetravalent platinum compound and aconcentrated aqueous solution of an alkali metal nitrate in theproportion of about nine molar weights of nitrate to one atomic weightof tetravalent platinum present in the platinum compound, heating theim- 75 pregnated material at a temperature of about 400 C. to formplatinum oxide, and extracting water-soluble impurities from theimpregnated material.

14. The method of preparing a hydrogenation catalyst which includesimpregnating an inert, porous support material with a concentratedaqueous solution of a water-soluble palladium divalent compound and aconcentrated aqueous solution of an alkali metal nitrate in theproportion of about four molar weights of nitrate to one atomic weightof divalent palladium present in the palladium compound, heating theimpregnated material'at a temperature of about 400 C. to form palladiumoxide, and extracting water-soluble impurities from the impregnatedmaterial.

15. The method of preparing a hydrogenation catalyst which includeseffecting a reaction between a water-soluble noble metal compound,

from the group consisting of platinum compounds and palladium compounds,and an alkali metal nitrate by bringing the reactants together inconcentrated aqueous solution, in amounts between aboutstoichiometrically equivalent amounts for a reaction to produce a noblemetal nitrate and about a 50% excess of the nitrate, and in the presenceof an inert, porous support material, heating the reaction mixture inthe presence of the support material to a temperature between about 300C. to about 450 C. whereby water is removed from the mixture and anoxide of the noble metal is firmly and adherently deposited upon thesupport material, and removing the water-soluble impurities from thecatalyst thus formed.

16. The method of preparing a hydrogenation catalyst which includesefiecting a reaction between a water-soluble platinum compound and analkali metal nitrate by bringing the reactants together in concentratedaqueous solution, in amounts between about stoichiometrically equivalentamounts tor a reaction to produce platinum nitrate and about a 50%excess of the nitrate, and in the presence of an inert, porous supportmaterial, heating the reaction mixture in the presence of the supportmaterial to a temperature between about 300 C. and about 450 C., wherebywater is removed from the mixture and an oxide of platinum is firmly andadherently deposited upon the support material, and removing thewater-soluble impurities from the catalyst thus formed.

1'7. The method of preparing a hydrogenation catalyst which includeseffecting a reaction between a water-soluble palladium compound and analkali metal nitrate by bringing the reactants together in concentratedaqueous solution, in

amounts between about stoichiometrically equivalent amounts for areaction to produce palladium nitrate and about a 50% excess of thenitrate, and in the presence of an inert, porous support material,heating the reaction mixture in the presence of the support material toa temperature between about 300 C. to about 450 0., whereby water isremoved from the mixture and an oxide of palladium is firmly andadherently deposited upon the support material, and removing thewater-soluble impurities from the catalyst thus formed.

18. A hydrogenation catalyst comprising an inert, porous supportmaterial impregnated with an adherent, uniform deposit of noble metaloxide from the group consisting of platinum oxides and palladium oxides,formed upon and in the presence of the porous support material by 7aaozsea the action, in situ, and at a temperature between about 300 C.to about 450 C. of a concentrated aqueous solution of an alkali metalnitrate upon a concentrated aqueous solution of a water-soluble, noblemetal compound.

19. A hydrogenation catalyst comprising an inert, porous supportmaterial impregnated with an adherent, uniform deposit of platinum oxideformed upon and in the presence of the porous support material by theaction, in situ, and at a temperature between about 300 C. to about 450C. of a concentrated aqueous solution of an alkali metal nitrate upon aconcentrated aqueous solution of a water-soluble platinum compound.

20. A hydrogenation catalyst comprising an inert, porous supportmaterial impregnated with an adherent, uniform deposit of palladiumoxide formed upon and in the presence of the porous support material bythe action, in situ, and at a temperature between about 300 C. to about450 C., of a. concentrated aqueous solution of an alkali metal nitrateupon a concentrated aqueous solution of a water-soluble palladiumcompound.

ROBERT W. MARTIN.

CERTIFICATE OF CORRECTION. Patent No. 2,207,868. July 16, 191w.

ROBERT w. MARTIN,

It is hereby certified that error appear's in the printedspecificationof the above numbered patent requiring'correction asfollows: Page 1, sec 0nd column, line 2, for "1 00 read "150"; line 8,for the word bias read --baae--- page 2, second column, line 7, for "75?read --57%'-; page 1;, second column, line 8, claim 114., strike out"divalent" and insert the same before alladium" in line 7, same claim;and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of the case in thePatentOffice.

Signed and sealed this 17th day of September, A. D. 191m.

Henry Van Arec iale, (Seal) Acting Commissioner of Patents.

